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NTIS

01/01/1988

Collation

19 pages ; 28 cm

Abstract

Quality control data collected during the measurement of ponderosa pine canopy cover and sugar maple crown damage was analyzed. Measurement precision (root mean square of differences in replicate measurements) of pine canopy cover was high (+or-2.6-4.0%) was similar for field replicates and laboratory replicates digitized with the same and different f-stops. In contrast, significant systematic errors can be introduced during certain analyses of hemispherical photographs. Measurement precision (frequency of remeasurement within +or- 1 class) of maple crown ratings was high (74-95%), due mainly to crew training prior to data collection. Precision was highest for branch dieback and foliage transparency and when remeasurements were done by the same crew. The following procedures are recommended: implement training prior to data collection, use consistent methods and reference materials to control measurement errors during data collection, and include methods and quality control data for a basis for evaluating data quality for comparability.

Notes

"Paper presented at the 'Effetcs of Air Pollution on Western Forests' Symposium (82nd AWMA Annual Meeting in Anaheim, CA, June 29-30, 1989.). Includes bibliographical references. "EPA/600/D-89/105"--Cover. Microfiche.

Supplementary Notes

Presented at the Effects of Air Pollution on Western Forests Symposium, Air and Waste Management Association Annual Meeting (82nd), Anaheim, CA., June 25-30, 1989. Prepared in cooperation with NSI Technology Services Corp., Corvallis, OR.